1. Field of the Invention.
The present invention relates to improvement in laundry machines and more particularly, to an improved balancing device for automatically correcting unbalance in rotors such as laundering machine wash drums which are spun at high speed to centrifugally extract fluid from laundered articles.
2. Description of Prior Art.
Centrifugal extraction is a commonly used expedient in laundering machines, especially in automatic home laundering machines, for the extraction of washing fluid from laundered articles after washing or rinsing period. Typically, at the termination of a laundering operation, the laundering container or wash drum is spun at high speeds for extracting the washing fluid from the laundered articles or clothes. A relatively high spinning speed is used for centrifugal extraction of the washing fluid from the washed clothes.
Frequently, however, the relatively heavy wet clothes are disposed within the wash drum in a unbalanced fashion creating an unbalanced condition during high speed spinning. The condition of having the load out of balance creates a condition where the center of mass of the rotating wash basket (with clothes load) does not correspond to the geometric axis of the wash basket. This leads to the generation of high loads and severe vibration of the wash basket. Furthermore, the severe vibration may cause the well known phenomenon of movement of the appliance across the floor. This unbalanced condition is particularly common in a wash drum having a horizontal axis, because the clothes load is more likely to gather on one side of the basket under the influence of gravity than in vertical axis washing machines.
Therefore, it is imperative that the wash basket be balanced to prevent excessive vibration and high loads. Correction of a wash basket unbalance, however, is frequently difficult as the location of the unbalance varies for each load and for each spin cycle and the amount of unbalance changes as fluid is extracted from the clothes.
One known method to overcome the above described problem and minimize the effect of the out-of-balance condition on the spinning wash drum is to secure to the wash drum heavy counter-balance weights. These counter-balance weights, usually large blocks of concrete or cast iron, are strapped to the outside of the rotatable drum for providing a fly wheel effect such that any unbalance due to uneven distribution of the clothes will be small relative to the mass of the counter-balance weights.
Another known method for overcoming the above described balancing problems is to utilize a movable liquid balancing system. For example, U.S. Pat. No. 4,991,247 utilizes a system having a sensor for sensing an out-of-balance condition and having means for responding to the sensed out-of-balance condition by introducing liquid into a plurality of cavities disposed along the outer periphery of the wash drum such that the rotating wash drum may be balanced. Other liquid balancing systems include balancing disks wherein the liquid shifts under centrifugal force to correct the unbalance such as U.S. Pat. No. 4,044,626.
Still another known movable liquid balancing system involves utilizing a plurality of concentric balancing disks, located across the periphery of a wash basket. U.S. Pat. No 2,525,781, issued to De Remer on Oct. 17, 1950 teaches the use of three concentric balancing disks disposed around the outer periphery of a vertical axis wash basket. De Remer further teaches the relative movement of the balancing disk assemblies with regard to the rotatable wash basket. Several disadvantages, however, are present in the balancing apparatus disclosed by De Remer. Water extraction for the rotating wash basket is impeded by the balancing disks disposed around the periphery of the wash basket. Further, the inner diameter of the balancing disk assembly is restricted to be no less than the outer diameter of the rotatable wash basket, thus limiting the effective number of balancing disks utilized. These disadvantages are such that, despite the advantages provided, the balancing system disclosed by De Remer has not met with widespread commercial acceptance in the home laundry market.
Accordingly, an object of the present invention is to provide an apparatus for balancing a rotatable wash drum which is relatively more sensitive to out-of-balance conditions than the forementioned prior art.
Another object of the present invention is to provide a balancing system which does not impede water extraction from the clothes through the outer periphery of the wash drum or cause pooling of water along the outer periphery of the wash drum.
Another object of the present invention is to provide a balancing system which allows for a large opening into the drum for top loading horizontal axis washing machines.
Another object of the present invention is to provide a balancing system which maximizes the restoring force generated for any given basket out-of-balance condition.
A still further object of the present invention is to provide a balancing system utilizing a plurality of concentric fluid filled balancing disks having an optimum number of balancing disks and being configured to not exceed the outer diameter of the rotatable wash drum.
A still further object of the present invention is to provide a horizontal rotatable wash basket construction having a balancing means for the rotatable wash basket according to the above stated objectives, the balancing means further forming opposite end walls of the rotatable wash basket.